Skip to main content
you & your car

What's the story with these multi-grade oils? They are much more expensive than the straight-weight stuff on my garage shelf, but car makers insist we use them. Is this just another attempt to take more money out of my wallet? – Cole in Mississauga, Ont.

Like everything else about today's motor vehicles, engines are more complex – but they also require far less care and maintenance. Some of this advance can be attributed to the oils developed in conjunction with the engines during extensive durability and stress testing.

In the old days, oils provided lubrication and the weight was chosen to ensure they did so under normal operating conditions and temperatures. There was little thought given to the fact engine temperatures ranged from below freezing at startup in some areas to near boiling at the other end of the spectrum and the fact the oil was too thick to provide proper lubrication when cold, and too thin to protect when hot.

As engines became more refined and car makers and lubrication engineers worked to ensure protection over a wide range of temperatures and conditions, multi-grade oils came into favour for their ability to adapt.

Let's not forget oil also acts as a coolant as it circulates through the system, carrying heat from around the cylinders to the oil pan sticking out in the cooling air stream below the car. At the same time the oil is carrying away contaminants, depositing them in the filter or boiling them off.

Oil plays an intricate role in ensuring long engine life and a cleaner atmosphere. And while it may be more expensive than used to be the case – what isn't? Actually, the amount you spend on oil over the life of an engine is probably lower because of the longer intervals between changes.

Oil has become an intricate part of ensuring long life and a cleaner atmosphere. That straight-weight oil in the garage is probably meant for an older small engine like a lawn mower or weed whacker or for mixing with gasoline for a two-cycle engine. Newer small four-cycle engines of this type also recommend multi-weight oils.

Wax and car washes

My friends suggest I apply a coat of wax to protect my car during the winter months. Is this necessary since I take it through a car wash every few weeks to get the salt off? – Shawna

You've got a conflict here. Yes, I recommend a coat of wax for protection – at all times of the year. But one trip through a commercial car wash will remove most of it.

The problem is that the soap used in the commercial wash has to be strong enough to cut through to remove some of the dirt without any actual scrubbing or surface motion. That same strength means it will break down and remove the wax.

For the same reason, you should not use dish or laundry detergent when washing your car by hand – the soap will cut through the wax.

In a perfect world, I would recommend waxing the vehicle at least two and probably three times a year. It might also be a good idea to take your car through a commercial wash to get the majority of the guck off and then doing a thorough hand wash and dry before applying wax.

Send your automotive maintenance and repair questions to